The ancient equivalent of a "Made in China" label allowed researchers to identify a previously mysterious sunken ship and examine how it fits into China's medieval history.
Centuries ago, a ship sailed from a Chinese port, filled with thousands of ceramics and luxury goods for trade. Unfortunately, the ship sank in the Java Sea off the coast of Indonesia. Slowly but surely, the ropes and sails started disintegrating and the wooden hull started disintegrating -- eventually, all that remained was the valuable cargo it was carrying.
The treasure lay at the bottom of the sea until the 1980s, when it was discovered by fishermen. Archaeologists first proposed that it dated back to the 13th century, but that theory is now reconsidered.
"Initial investigations in the 1990s dated the shipwreck to the mid- to late 13th century, but we've found evidence that it's probably a century older than that," says Lisa Niziolek, an archaeologist at the Field Museum in Chicago and lead author of the study in the Journal of Archaeological Science: Reports. "Eight hundred years ago, someone put a label on these ceramics that essentially says 'Made in China'--because of the particular place mentioned, we're able to date this shipwreck better."
The ship was carrying ceramics marked with an inscription that might indicate they were made in Jianning Fu, a government district in China. However, what’s special about Jianning Fu is that it can serve as an accurate dating tool, since it was invaded by the Mongolians and reclassified as Jianning Lu in 1278. This, therefore, seals the top date, since it's very unlikely that any pottery after 1278 would be carrying the outdated name.
"There were probably about a hundred thousand pieces of ceramics onboard. It seems unlikely a merchant would have paid to store those for long prior to shipment--they were probably made not long before the ship sank," says Niziolek.
But Niziolek and his colleagues say the ship likely set sail way before 1278. Among other things, the treasure they analyzed also contained elephant tusks and sweet-smelling resin for use in incense or for caulking ships -- both these materials are important for dating the ship.
Both the resin and the tusks contain carbon, and carbon can be used for radiocarbon dating. Essentially, an isotope of carbon called C-14 is unstable and decays steadily over time. By analyzing how much C-14 a sample has, researchers can date the sample reasonably well.
The first analysis indicated an age of 700-750 years, but since the first analysis, analytical methods have improved significantly. Using the latest available methods, the new study reports that the ship was more likely around 800 years old.
"When we got the results back and learned that the resin and tusk samples were older than previously thought, we were excited," says Niziolek. "We had suspected that based on inscriptions on the ceramics and conversations with colleagues in China and Japan, and it was great to have all these different types of data coming together to support it."
It may seem like a trivial difference, but changing the dating of the ship from 700 to 800 years old is actually very important, since it comes from a time where important transitions were taking place in China and the rest of Asia: the legendary Silk Road was starting its decline as sea routes saw more and more use.
"This was a time when Chinese merchants became more active in maritime trade, more reliant upon oversea routes than on the overland Silk Road," says Niziolek. "The shipwreck occurred at a time of important transition."
The results have been published in Journal of Archaeological Science: Reports.